Scott Robinson drills into a hemlock in preparation for administering a pesticide by injection. SANDRA PHINNEY PHOTO

A Yarmouth County couple hope a newly approved pesticide applied to their hemlocks by Shelburne arborist Scott Robinson will control an insect that’s killing the trees on their property.

Canaan residents Sandra Phinney and Barrie MacGregor hosted a workshop in January with Colin Gray, a field researcher with the Mersey Tobeatic Research Institute, on the topic of the hemlock woolly adelgid (HWA).

The insect sucks the sap from trees and can be spread by wind and animals. It can also be spread by people moving things like nursery stock, logs or firewood.

MacGregor says to his knowledge there is no readily available treatment for the adelgid up to the present.

“So something on an experimental basis is welcome. I'm not up to speed on any research, but we're willing to be guinea pigs, as well as investing some money in treatment above and beyond,” he said.

He noticed small dandruff-like white spots on needles and obvious damage to at least 20 of their hemlock trees last fall.

The trees look frail when compared to the balsam fir standing close by.

A great video that explains how Hemlock Woolly Adelgid will impact our ecosystem:

“Difficult to tell how badly off they are as they are more than 40 feet tall. Obviously losing all those trees would be a visual disaster as well as damaging to the riparian buffer (shoreline protection),” he said.

Enter Robinson. He’s been an arborist for over 30 years and sells technology packages to golf courses to help them manage their trees.

His wife’s favourite tree is hemlock and they have many on their Lake Deception property. After reading about HWA, he checked their hemlocks and found the pest on the first five trees he checked. The sight alarmed him, as he had recently travelled to the mountains of North Carolina, where any tree that had not been treated with the pesticide imidacloprid, or a similar product, had been killed by HWA.

Before treating his trees and offering his service he talked to property managers with hemlock in areas that have HWA and the approval to use imidacloprid.

“They told me that hemlock that were not treated with a product similar to imidacloprid are all dead.”

The product is injected into the trunk of the tree and the sap carries it to the affected needles on the trees.

The active ingredient reaches the affected parts within 48 hours.

“When the HWA takes their first nibble, it’s their last,” said Robinson.

The treatment needs to be repeated every three years and isn’t cheap. The cost for treating a 20-inch tree is between $200 and $300.
The value of a healthy mature hemlock, however, is significant. Robinson is available to treat hemlocks within the province. Incidentally, many pet owners have likely been applying imidacloprid to their dogs and cats for years. It’s the active ingredient in many topical flea and tick treatments.